Children hold posters depicting Yasser Arafat, right, and Mahmoud Abbas as they take part in a vigil in support of Palestine's efforts to secure a diplomatic upgrade at the U.N. in the Balata refugee camp near the West Bank city of Nablus on Nov. 28, 2012

Nothing in the appearance of the four-story building with a Hyundai dealership downstairs suggests that it is particularly special in the commercial section of Lausanne, Switzerland. But on its secure upper floors, a highly sensitive examination is taking place, one with potentially international ramifications.

The nondescript building houses the Swiss Institute of Radiation Physics (IRA), a state-funded institution affiliated with Lausanne’s University Hospital (CHUV) and the University of Lausanne’s Medical School. There, forensic scientists are analyzing samples taken from Yasser Arafat’s remains, exhumed in the West Bank city of Ramallah at the end of November. They are looking for traces of polonium, a toxic radioactive substance that, his widow and political allies suspect, had poisoned the 75-year-old Palestinian leader and led to his death in a Paris hospital in November 2004. The official cause reported at the time was a massive stroke.

The Palestinian National Authority, which runs the West Bank where Arafat was buried, claims that Israel is behind the conjectured poisoning, a charge that the Israeli government denies.

Earlier this year, the institute was commissioned by the Arab al-Jazeera TV channel, which had conducted its own investigation into Arafat’s death and raised suspicions of foul play when it alleged that Arafat had been healthy a month before a sudden illness took his life. The IRA was asked to test the late leader’s personal effects provided by his widow, Suha. Clayton Swisher, the al-Jazeera journalist who investigated Arafat’s death and allegations of poisoning, tells TIME he chose the IRA because it had an in-house toxicology lab, as well as the capability to handle this particular type of analysis. “The greater appeal of choosing Swiss scientists,” Swisher says, “is that they have the least political baggage. Would Palestinians trust analysis done by American physicians in New York? Would Israelis trust analysis done by German scientists in Berlin? Switzerland fit the bill.”

As it turned out during that first test in July, IRA’s scientists discovered unusually high levels of polonium on Arafat’s clothing, toothbrush and kaffiyeh, a traditional black-and-white scarf he wore on his head. “We found traces of polonium on Mr. Arafat’s personal belongings, but never suggested he was poisoned,” CHUV spokesman Darcy Christen, who was part of the Ramallah delegation, tells TIME.

The finding sparked Palestinian calls for the exhumation of Arafat’s remains before any traces of polonium would disappear — the substance usually decays after eight years. At the end of November, IRA scientists assisted, along with the French and Russian experts, in the exhumation.

However, experts say that even though the samples were collected within the eight-year time frame, the results might be inconclusive. Jean-René Jourdain, from the French Institute for Radiological Protection and Nuclear Safety, told Agence France-Presse last week that even if traces of polonium are detected, “it doesn’t mean that they were man-made”; a naturally occurring polonium that exists everywhere in our environment at low concentrations might have somehow contaminated the Palestinian leader. “The key for our physicists is to differentiate natural polonium from artificial one, which, eight years after Mr. Arafat’s death is a rather complex process,” Christen says.

Although the cost of the operation remains secret, no Swiss funds are used for this, or any other of the IRA’s private mandates. “We quoted a price based on official Swiss rates, and the Palestinian Authority accepted it,” Christen says, adding that the findings of the investigation will only be released in four or five months.

This week, Dr. Patrice Mangin and a team of Swiss scientists are starting the time-consuming work of analyzing the samples, during which the IRA premises will be off-limits to the public. “This was one of the most emotional experiences of my career,” Mangin told the newspaper Le Matin last Sunday, after his return from Ramallah. He added that his team had brought 60 kg of their own equipment, packed in six suitcases, which surprised members of the other delegations.

Though he and others gathered at Arafat’s graveside were instructed by the Palestinian Authority not to reveal the specifics of the exhumation or the state of the remains, Mangin described how he and other scientists descended about 4 m on the makeshift stairs to reach the grave, “while the officials watched us from above.” In a laboratory set up in a nearby mosque where the body was moved, Mangin was able to extract about 60 samples, a sufficient amount, he said, to identify the remains, confirm the presence of polonium and conduct a toxicological analysis. Whether that analysis will be enough to prove or disprove suspicion is, of course, not a matter of science.